From c515cb9b5f440db47527cedb0b2e92a3b1da8552 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 14 Nov 2022 16:19:20 -0800
Subject: [PATCH 1/5] initial padding options

---
 src/Window.zig           |  7 ++++++-
 src/config.zig           | 21 +++++++++++++++++++++
 src/renderer.zig         |  1 +
 src/renderer/OpenGL.zig  | 28 +++++++++++++++++-----------
 src/renderer/Options.zig | 21 +++++++++++++++++++++
 src/renderer/size.zig    |  8 ++++----
 6 files changed, 70 insertions(+), 16 deletions(-)
 create mode 100644 src/renderer/Options.zig

diff --git a/src/Window.zig b/src/Window.zig
index 6d8b87f68..d03137016 100644
--- a/src/Window.zig
+++ b/src/Window.zig
@@ -260,7 +260,12 @@ pub fn create(alloc: Allocator, app: *App, config: *const Config) !*Window {
     errdefer font_group.deinit(alloc);
 
     // Create our terminal grid with the initial window size
-    var renderer_impl = try Renderer.init(alloc, font_group);
+    var renderer_impl = try Renderer.init(alloc, .{
+        .font_group = font_group,
+        .padding = .{
+            .balance = config.@"window-padding-balance",
+        },
+    });
     errdefer renderer_impl.deinit();
     renderer_impl.background = .{
         .r = config.background.r,
diff --git a/src/config.zig b/src/config.zig
index 341b41bb8..796894d37 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -89,6 +89,27 @@ pub const Config = struct {
     ///
     keybind: Keybinds = .{},
 
+    /// Window padding. This applies padding between the terminal cells and
+    /// the window border. The "x" option applies to the left and right
+    /// padding and the "y" option is top and bottom. The value is in points,
+    /// meaning that it will be scaled appropriately for screen DPI.
+    @"window-padding-x": u32 = 0,
+    @"window-padding-y": u32 = 0,
+
+    /// The viewport dimensions are usually not perfectly divisible by
+    /// the cell size. In this case, some extra padding on the end of a
+    /// column and the bottom of the final row may exist. If this is true,
+    /// then this extra padding is automatically balanced between all four
+    /// edges to minimize imbalance on one side. If this is false, the top
+    /// left grid cell will always hug the edge with zero padding other than
+    /// what may be specified with the other "window-padding" options.
+    ///
+    /// If other "window-padding" fields are set and this is true, this will
+    /// still apply. The other padding is applied first and may affect how
+    /// many grid cells actually exist, and this is applied last in order
+    /// to balance the padding given a certain viewport size and grid cell size.
+    @"window-padding-balance": bool = true,
+
     /// Additional configuration files to read.
     @"config-file": RepeatableString = .{},
 
diff --git a/src/renderer.zig b/src/renderer.zig
index 8d2a2fe40..f52cff302 100644
--- a/src/renderer.zig
+++ b/src/renderer.zig
@@ -14,6 +14,7 @@ pub usingnamespace @import("renderer/message.zig");
 pub usingnamespace @import("renderer/size.zig");
 pub const Metal = @import("renderer/Metal.zig");
 pub const OpenGL = @import("renderer/OpenGL.zig");
+pub const Options = @import("renderer/Options.zig");
 pub const Thread = @import("renderer/Thread.zig");
 pub const State = @import("renderer/State.zig");
 
diff --git a/src/renderer/OpenGL.zig b/src/renderer/OpenGL.zig
index 076bcd2bb..fea033d9b 100644
--- a/src/renderer/OpenGL.zig
+++ b/src/renderer/OpenGL.zig
@@ -77,6 +77,9 @@ background: terminal.color.RGB,
 /// True if the window is focused
 focused: bool,
 
+/// Padding options
+padding: renderer.Options.Padding,
+
 /// The raw structure that maps directly to the buffer sent to the vertex shader.
 /// This must be "extern" so that the field order is not reordered by the
 /// Zig compiler.
@@ -146,7 +149,7 @@ const GPUCellMode = enum(u8) {
     }
 };
 
-pub fn init(alloc: Allocator, font_group: *font.GroupCache) !OpenGL {
+pub fn init(alloc: Allocator, options: renderer.Options) !OpenGL {
     // Create the initial font shaper
     var shape_buf = try alloc.alloc(font.Shaper.Cell, 1);
     errdefer alloc.free(shape_buf);
@@ -157,8 +160,8 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !OpenGL {
     // Doesn't matter, any normal ASCII will do we're just trying to make
     // sure we use the regular font.
     const metrics = metrics: {
-        const index = (try font_group.indexForCodepoint(alloc, 'M', .regular, .text)).?;
-        const face = try font_group.group.faceFromIndex(index);
+        const index = (try options.font_group.indexForCodepoint(alloc, 'M', .regular, .text)).?;
+        const face = try options.font_group.group.faceFromIndex(index);
         break :metrics face.metrics;
     };
     log.debug("cell dimensions={}", .{metrics});
@@ -248,12 +251,12 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !OpenGL {
         try texbind.image2D(
             0,
             .Red,
-            @intCast(c_int, font_group.atlas_greyscale.size),
-            @intCast(c_int, font_group.atlas_greyscale.size),
+            @intCast(c_int, options.font_group.atlas_greyscale.size),
+            @intCast(c_int, options.font_group.atlas_greyscale.size),
             0,
             .Red,
             .UnsignedByte,
-            font_group.atlas_greyscale.data.ptr,
+            options.font_group.atlas_greyscale.data.ptr,
         );
     }
 
@@ -269,12 +272,12 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !OpenGL {
         try texbind.image2D(
             0,
             .RGBA,
-            @intCast(c_int, font_group.atlas_color.size),
-            @intCast(c_int, font_group.atlas_color.size),
+            @intCast(c_int, options.font_group.atlas_color.size),
+            @intCast(c_int, options.font_group.atlas_color.size),
             0,
             .BGRA,
             .UnsignedByte,
-            font_group.atlas_color.data.ptr,
+            options.font_group.atlas_color.data.ptr,
         );
     }
 
@@ -289,13 +292,14 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !OpenGL {
         .vbo = vbo,
         .texture = tex,
         .texture_color = tex_color,
-        .font_group = font_group,
+        .font_group = options.font_group,
         .font_shaper = shaper,
         .cursor_visible = true,
         .cursor_style = .box,
         .background = .{ .r = 0, .g = 0, .b = 0 },
         .foreground = .{ .r = 255, .g = 255, .b = 255 },
         .focused = true,
+        .padding = options.padding,
     };
 }
 
@@ -952,7 +956,9 @@ fn setScreenSize(self: *OpenGL, dim: renderer.ScreenSize) !void {
     // Determine if we need to pad the window. For "auto" padding, we take
     // the leftover amounts on the right/bottom that don't fit a full grid cell
     // and we split them equal across all boundaries.
-    const padding = renderer.Padding.balanced(dim, grid_size, self.cell_size);
+    const padding: renderer.Padding = if (self.padding.balance)
+        renderer.Padding.balanced(dim, grid_size, self.cell_size)
+    else .{};
     const padded_dim = dim.subPadding(padding);
 
     log.debug("screen size padded={} screen={} grid={} cell={}", .{ padded_dim, dim, grid_size, self.cell_size });
diff --git a/src/renderer/Options.zig b/src/renderer/Options.zig
new file mode 100644
index 000000000..f4e083537
--- /dev/null
+++ b/src/renderer/Options.zig
@@ -0,0 +1,21 @@
+//! The options that are used to configure a renderer.
+
+const font = @import("../font/main.zig");
+
+/// The font group that should be used.
+font_group: *font.GroupCache,
+
+/// Padding options for the viewport.
+padding: Padding,
+
+pub const Padding = struct {
+    // Explicit padding options, in pixels. The windowing thread is
+    // expected to convert points to pixels for a given DPI.
+    top: u32 = 0,
+    bottom: u32 = 0,
+    right: u32 = 0,
+    left: u32 = 0,
+
+    // Balance options
+    balance: bool = false,
+};
diff --git a/src/renderer/size.zig b/src/renderer/size.zig
index 849603941..c59ffb944 100644
--- a/src/renderer/size.zig
+++ b/src/renderer/size.zig
@@ -78,10 +78,10 @@ pub const GridSize = struct {
 
 /// The padding to add to a screen.
 pub const Padding = struct {
-    top: f32,
-    bottom: f32,
-    right: f32,
-    left: f32,
+    top: f32 = 0,
+    bottom: f32 = 0,
+    right: f32 = 0,
+    left: f32 = 0,
 
     /// Returns padding that balances the whitespace around the screen
     /// for the given grid and cell sizes.

From d7d12d9469e400db3a29b0e6dd1d64265e784293 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 14 Nov 2022 17:13:56 -0800
Subject: [PATCH 2/5] explicit padding works

---
 src/Window.zig           | 21 ++++++++++++++++++---
 src/cli_args.zig         |  6 ++++++
 src/renderer/OpenGL.zig  | 31 ++++++++++++++++++++++---------
 src/renderer/Options.zig |  6 ++----
 src/renderer/size.zig    | 10 ++++++++++
 5 files changed, 58 insertions(+), 16 deletions(-)

diff --git a/src/Window.zig b/src/Window.zig
index d03137016..1ea177465 100644
--- a/src/Window.zig
+++ b/src/Window.zig
@@ -82,6 +82,9 @@ io_thr: std.Thread,
 /// The dimensions of the grid in rows and columns.
 grid_size: renderer.GridSize,
 
+/// Explicit padding due to configuration
+padding: renderer.Padding,
+
 /// The app configuration
 config: *const Config,
 
@@ -259,10 +262,21 @@ pub fn create(alloc: Allocator, app: *App, config: *const Config) !*Window {
     });
     errdefer font_group.deinit(alloc);
 
+    // Convert our padding from points to pixels
+    const padding_x = (@intToFloat(f32, config.@"window-padding-x") * x_dpi) / 72;
+    const padding_y = (@intToFloat(f32, config.@"window-padding-y") * y_dpi) / 72;
+    const padding: renderer.Padding = .{
+        .top = padding_y,
+        .bottom = padding_y,
+        .right = padding_x,
+        .left = padding_x,
+    };
+
     // Create our terminal grid with the initial window size
     var renderer_impl = try Renderer.init(alloc, .{
         .font_group = font_group,
         .padding = .{
+            .explicit = padding,
             .balance = config.@"window-padding-balance",
         },
     });
@@ -284,7 +298,7 @@ pub fn create(alloc: Allocator, app: *App, config: *const Config) !*Window {
         .width = window_size.width,
         .height = window_size.height,
     };
-    const grid_size = renderer.GridSize.init(screen_size, renderer_impl.cell_size);
+    const grid_size = renderer_impl.gridSize(screen_size);
 
     // Set a minimum size that is cols=10 h=4. This matches Mac's Terminal.app
     // but is otherwise somewhat arbitrary.
@@ -358,6 +372,7 @@ pub fn create(alloc: Allocator, app: *App, config: *const Config) !*Window {
         .io_thread = io_thread,
         .io_thr = undefined,
         .grid_size = grid_size,
+        .padding = padding,
         .config = config,
 
         .imgui_ctx = if (!DevMode.enabled) {} else try imgui.Context.create(),
@@ -565,13 +580,13 @@ fn sizeCallback(window: glfw.Window, width: i32, height: i32) void {
     // overhead of inter-thread communication
 
     // Recalculate our grid size
-    win.grid_size.update(screen_size, win.renderer.cell_size);
+    win.grid_size = win.renderer.gridSize(screen_size);
 
     // Mail the IO thread
     _ = win.io_thread.mailbox.push(.{
         .resize = .{
             .grid_size = win.grid_size,
-            .screen_size = screen_size,
+            .screen_size = screen_size.subPadding(win.padding),
         },
     }, .{ .forever = {} });
     win.io_thread.wakeup.send() catch {};
diff --git a/src/cli_args.zig b/src/cli_args.zig
index 97bae03c3..4167b6085 100644
--- a/src/cli_args.zig
+++ b/src/cli_args.zig
@@ -138,6 +138,12 @@ fn parseIntoField(
                     0,
                 ),
 
+                u32 => try std.fmt.parseInt(
+                    u32,
+                    value orelse return error.ValueRequired,
+                    0,
+                ),
+
                 else => unreachable,
             };
 
diff --git a/src/renderer/OpenGL.zig b/src/renderer/OpenGL.zig
index fea033d9b..41f025206 100644
--- a/src/renderer/OpenGL.zig
+++ b/src/renderer/OpenGL.zig
@@ -947,21 +947,34 @@ pub fn updateCell(
     return true;
 }
 
+/// Returns the grid size for a given screen size. This is safe to call
+/// on any thread.
+pub fn gridSize(self: *OpenGL, screen_size: renderer.ScreenSize) renderer.GridSize {
+    return renderer.GridSize.init(
+        screen_size.subPadding(self.padding.explicit),
+        self.cell_size,
+    );
+}
+
 /// Set the screen size for rendering. This will update the projection
 /// used for the shader so that the scaling of the grid is correct.
 fn setScreenSize(self: *OpenGL, dim: renderer.ScreenSize) !void {
     // Recalculate the rows/columns.
-    const grid_size = renderer.GridSize.init(dim, self.cell_size);
+    const grid_size = self.gridSize(dim);
 
-    // Determine if we need to pad the window. For "auto" padding, we take
-    // the leftover amounts on the right/bottom that don't fit a full grid cell
-    // and we split them equal across all boundaries.
-    const padding: renderer.Padding = if (self.padding.balance)
+    // Apply our padding
+    const padding = self.padding.explicit.add(if (self.padding.balance)
         renderer.Padding.balanced(dim, grid_size, self.cell_size)
-    else .{};
+    else .{});
     const padded_dim = dim.subPadding(padding);
 
-    log.debug("screen size padded={} screen={} grid={} cell={}", .{ padded_dim, dim, grid_size, self.cell_size });
+    log.debug("screen size padded={} screen={} grid={} cell={} padding={}", .{
+        padded_dim,
+        dim,
+        grid_size,
+        self.cell_size,
+        self.padding.explicit,
+    });
 
     // Update our LRU. We arbitrarily support a certain number of pages here.
     // We also always support a minimum number of caching in case a user
@@ -997,8 +1010,8 @@ fn setScreenSize(self: *OpenGL, dim: renderer.ScreenSize) !void {
             // 2D orthographic projection with the full w/h
             math.ortho2d(
                 -1 * padding.left,
-                @intToFloat(f32, padded_dim.width),
-                @intToFloat(f32, padded_dim.height),
+                @intToFloat(f32, padded_dim.width) + padding.right,
+                @intToFloat(f32, padded_dim.height) + padding.bottom,
                 -1 * padding.top,
             ),
         );
diff --git a/src/renderer/Options.zig b/src/renderer/Options.zig
index f4e083537..c313d91c6 100644
--- a/src/renderer/Options.zig
+++ b/src/renderer/Options.zig
@@ -1,6 +1,7 @@
 //! The options that are used to configure a renderer.
 
 const font = @import("../font/main.zig");
+const renderer = @import("../renderer.zig");
 
 /// The font group that should be used.
 font_group: *font.GroupCache,
@@ -11,10 +12,7 @@ padding: Padding,
 pub const Padding = struct {
     // Explicit padding options, in pixels. The windowing thread is
     // expected to convert points to pixels for a given DPI.
-    top: u32 = 0,
-    bottom: u32 = 0,
-    right: u32 = 0,
-    left: u32 = 0,
+    explicit: renderer.Padding,
 
     // Balance options
     balance: bool = false,
diff --git a/src/renderer/size.zig b/src/renderer/size.zig
index c59ffb944..51a3b135c 100644
--- a/src/renderer/size.zig
+++ b/src/renderer/size.zig
@@ -112,6 +112,16 @@ pub const Padding = struct {
             .left = padding_left,
         };
     }
+
+    /// Add another padding to ths one
+    pub fn add(self: Padding, other: Padding) Padding {
+        return .{
+            .top = self.top + other.top,
+            .bottom = self.bottom + other.bottom,
+            .right = self.right + other.right,
+            .left = self.left + other.left,
+        };
+    }
 };
 
 test "GridSize update exact" {

From 860fbc3aee45e6e49fd9156e3913e9dd09f61288 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 14 Nov 2022 17:25:35 -0800
Subject: [PATCH 3/5] padding needs to be sent to termio

---
 src/Window.zig         | 3 ++-
 src/termio/Exec.zig    | 7 +++++--
 src/termio/Thread.zig  | 2 +-
 src/termio/message.zig | 8 ++++++++
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/Window.zig b/src/Window.zig
index 1ea177465..a96cd73fb 100644
--- a/src/Window.zig
+++ b/src/Window.zig
@@ -586,7 +586,8 @@ fn sizeCallback(window: glfw.Window, width: i32, height: i32) void {
     _ = win.io_thread.mailbox.push(.{
         .resize = .{
             .grid_size = win.grid_size,
-            .screen_size = screen_size.subPadding(win.padding),
+            .screen_size = screen_size,
+            .padding = win.padding,
         },
     }, .{ .forever = {} });
     win.io_thread.wakeup.send() catch {};
diff --git a/src/termio/Exec.zig b/src/termio/Exec.zig
index 8926ea671..cb7b8f6e6 100644
--- a/src/termio/Exec.zig
+++ b/src/termio/Exec.zig
@@ -231,13 +231,16 @@ pub fn resize(
     self: *Exec,
     grid_size: renderer.GridSize,
     screen_size: renderer.ScreenSize,
+    padding: renderer.Padding,
 ) !void {
+    const padded_size = screen_size.subPadding(padding);
+
     // Update the size of our pty
     try self.pty.setSize(.{
         .ws_row = @intCast(u16, grid_size.rows),
         .ws_col = @intCast(u16, grid_size.columns),
-        .ws_xpixel = @intCast(u16, screen_size.width),
-        .ws_ypixel = @intCast(u16, screen_size.height),
+        .ws_xpixel = @intCast(u16, padded_size.width),
+        .ws_ypixel = @intCast(u16, padded_size.height),
     });
 
     // Update our cached grid size
diff --git a/src/termio/Thread.zig b/src/termio/Thread.zig
index e8db4d3ff..7c75d9603 100644
--- a/src/termio/Thread.zig
+++ b/src/termio/Thread.zig
@@ -172,7 +172,7 @@ fn drainMailbox(self: *Thread) !void {
 
             log.debug("mailbox message={}", .{message});
             switch (message) {
-                .resize => |v| try self.impl.resize(v.grid_size, v.screen_size),
+                .resize => |v| try self.impl.resize(v.grid_size, v.screen_size, v.padding),
                 .write_small => |v| try self.impl.queueWrite(v.data[0..v.len]),
                 .write_stable => |v| try self.impl.queueWrite(v),
                 .write_alloc => |v| {
diff --git a/src/termio/message.zig b/src/termio/message.zig
index 623c41b40..9c03cf1e6 100644
--- a/src/termio/message.zig
+++ b/src/termio/message.zig
@@ -12,8 +12,16 @@ const terminal = @import("../terminal/main.zig");
 pub const Message = union(enum) {
     /// Resize the window.
     resize: struct {
+        /// The grid size for the given screen size with padding applied.
         grid_size: renderer.GridSize,
+
+        /// The full screen (drawable) size. This does NOT include padding.
+        /// This should be sent on to the renderer.
         screen_size: renderer.ScreenSize,
+
+        /// The padding, so that the terminal implementation can subtract
+        /// this to send to the pty.
+        padding: renderer.Padding,
     },
 
     /// Write where the data fits in the union.

From e6c7fd02147165f63a725b413ea811c8cd702162 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 14 Nov 2022 17:35:10 -0800
Subject: [PATCH 4/5] metal: understand explicit padding

---
 src/renderer/Metal.zig | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/src/renderer/Metal.zig b/src/renderer/Metal.zig
index 3985d7c6c..a565df99f 100644
--- a/src/renderer/Metal.zig
+++ b/src/renderer/Metal.zig
@@ -33,6 +33,9 @@ alloc: std.mem.Allocator,
 /// Current cell dimensions for this grid.
 cell_size: renderer.CellSize,
 
+/// Explicit padding.
+padding: renderer.Options.Padding,
+
 /// True if the window is focused
 focused: bool,
 
@@ -130,7 +133,7 @@ pub fn windowInit(window: glfw.Window) !void {
     // else up during actual initialization.
 }
 
-pub fn init(alloc: Allocator, font_group: *font.GroupCache) !Metal {
+pub fn init(alloc: Allocator, options: renderer.Options) !Metal {
     // Initialize our metal stuff
     const device = objc.Object.fromId(MTLCreateSystemDefaultDevice());
     const queue = device.msgSend(objc.Object, objc.sel("newCommandQueue"), .{});
@@ -150,8 +153,8 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !Metal {
     // Doesn't matter, any normal ASCII will do we're just trying to make
     // sure we use the regular font.
     const metrics = metrics: {
-        const index = (try font_group.indexForCodepoint(alloc, 'M', .regular, .text)).?;
-        const face = try font_group.group.faceFromIndex(index);
+        const index = (try options.font_group.indexForCodepoint(alloc, 'M', .regular, .text)).?;
+        const face = try options.font_group.group.faceFromIndex(index);
         break :metrics face.metrics;
     };
     log.debug("cell dimensions={}", .{metrics});
@@ -200,12 +203,13 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !Metal {
     // Initialize our shader (MTLLibrary)
     const library = try initLibrary(device, @embedFile("../shaders/cell.metal"));
     const pipeline_state = try initPipelineState(device, library);
-    const texture_greyscale = try initAtlasTexture(device, &font_group.atlas_greyscale);
-    const texture_color = try initAtlasTexture(device, &font_group.atlas_color);
+    const texture_greyscale = try initAtlasTexture(device, &options.font_group.atlas_greyscale);
+    const texture_color = try initAtlasTexture(device, &options.font_group.atlas_color);
 
     return Metal{
         .alloc = alloc,
         .cell_size = .{ .width = metrics.cell_width, .height = metrics.cell_height },
+        .padding = options.padding,
         .background = .{ .r = 0, .g = 0, .b = 0 },
         .foreground = .{ .r = 255, .g = 255, .b = 255 },
         .focused = true,
@@ -224,7 +228,7 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !Metal {
         },
 
         // Fonts
-        .font_group = font_group,
+        .font_group = options.font_group,
         .font_shaper = font_shaper,
 
         // Metal stuff
@@ -302,6 +306,15 @@ pub fn threadExit(self: *const Metal) void {
     // Metal requires no per-thread state.
 }
 
+/// Returns the grid size for a given screen size. This is safe to call
+/// on any thread.
+pub fn gridSize(self: *Metal, screen_size: renderer.ScreenSize) renderer.GridSize {
+    return renderer.GridSize.init(
+        screen_size.subPadding(self.padding.explicit),
+        self.cell_size,
+    );
+}
+
 /// Callback when the focus changes for the terminal this is rendering.
 pub fn setFocus(self: *Metal, focus: bool) !void {
     self.focused = focus;
@@ -562,12 +575,14 @@ fn setScreenSize(self: *Metal, bounds: macos.graphics.Size) !void {
     };
 
     // Recalculate the rows/columns.
-    const grid_size = renderer.GridSize.init(dim, self.cell_size);
+    const grid_size = self.gridSize(dim);
 
     // Determine if we need to pad the window. For "auto" padding, we take
     // the leftover amounts on the right/bottom that don't fit a full grid cell
     // and we split them equal across all boundaries.
-    const padding = renderer.Padding.balanced(dim, grid_size, self.cell_size);
+    const padding = self.padding.explicit.add(if (self.padding.balance)
+        renderer.Padding.balanced(dim, grid_size, self.cell_size)
+    else .{});
     const padded_dim = dim.subPadding(padding);
 
     // Update our shaper
@@ -585,8 +600,8 @@ fn setScreenSize(self: *Metal, bounds: macos.graphics.Size) !void {
     self.uniforms = .{
         .projection_matrix = math.ortho2d(
             -1 * padding.left,
-            @intToFloat(f32, padded_dim.width),
-            @intToFloat(f32, padded_dim.height),
+            @intToFloat(f32, padded_dim.width) + padding.right,
+            @intToFloat(f32, padded_dim.height) + padding.bottom,
             -1 * padding.top,
         ),
         .cell_size = .{ self.cell_size.width, self.cell_size.height },

From 334743e8a7182fd7f233cbcf7c4a057700d7c7fe Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 14 Nov 2022 17:41:15 -0800
Subject: [PATCH 5/5] Don't crash on huge padding, warn users if padding is
 absurd

---
 src/Window.zig        | 8 ++++++++
 src/config.zig        | 5 +++++
 src/renderer/size.zig | 8 ++++----
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/Window.zig b/src/Window.zig
index a96cd73fb..ad1b9b836 100644
--- a/src/Window.zig
+++ b/src/Window.zig
@@ -581,6 +581,14 @@ fn sizeCallback(window: glfw.Window, width: i32, height: i32) void {
 
     // Recalculate our grid size
     win.grid_size = win.renderer.gridSize(screen_size);
+    if (win.grid_size.columns < 5 and (win.padding.left > 0 or win.padding.right > 0)) {
+        log.warn("WARNING: very small terminal grid detected with padding " ++
+            "set. Is your padding reasonable?", .{});
+    }
+    if (win.grid_size.rows < 2 and (win.padding.top > 0 or win.padding.bottom > 0)) {
+        log.warn("WARNING: very small terminal grid detected with padding " ++
+            "set. Is your padding reasonable?", .{});
+    }
 
     // Mail the IO thread
     _ = win.io_thread.mailbox.push(.{
diff --git a/src/config.zig b/src/config.zig
index 796894d37..d7a60753e 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -93,6 +93,11 @@ pub const Config = struct {
     /// the window border. The "x" option applies to the left and right
     /// padding and the "y" option is top and bottom. The value is in points,
     /// meaning that it will be scaled appropriately for screen DPI.
+    ///
+    /// If this value is set too large, the screen will render nothing, because
+    /// the grid will be completely squished by the padding. It is up to you
+    /// as the user to pick a reasonable value. If you pick an unreasonable
+    /// value, a warning will appear in the logs.
     @"window-padding-x": u32 = 0,
     @"window-padding-y": u32 = 0,
 
diff --git a/src/renderer/size.zig b/src/renderer/size.zig
index 51a3b135c..a96ae160e 100644
--- a/src/renderer/size.zig
+++ b/src/renderer/size.zig
@@ -48,8 +48,8 @@ pub const ScreenSize = struct {
     /// Subtract padding from the screen size.
     pub fn subPadding(self: ScreenSize, padding: Padding) ScreenSize {
         return .{
-            .width = self.width - @floatToInt(u32, padding.left + padding.right),
-            .height = self.height - @floatToInt(u32, padding.top + padding.bottom),
+            .width = self.width -| @floatToInt(u32, padding.left + padding.right),
+            .height = self.height -| @floatToInt(u32, padding.top + padding.bottom),
         };
     }
 };
@@ -71,8 +71,8 @@ pub const GridSize = struct {
     /// Update the columns/rows for the grid based on the given screen and
     /// cell size.
     pub fn update(self: *GridSize, screen: ScreenSize, cell: CellSize) void {
-        self.columns = @floatToInt(Unit, @intToFloat(f32, screen.width) / cell.width);
-        self.rows = @floatToInt(Unit, @intToFloat(f32, screen.height) / cell.height);
+        self.columns = @max(1, @floatToInt(Unit, @intToFloat(f32, screen.width) / cell.width));
+        self.rows = @max(1, @floatToInt(Unit, @intToFloat(f32, screen.height) / cell.height));
     }
 };